Study Finds Forest Growth Dictated By Bedrock, Not Just Climate

A study by UW scientists finds that bedrock plays as big of a role as climate in determining how much vegetation grows in an area.

Bedrock is the layer of rock beneath the soil.

Lead author Jesse Hahm says he did the research because he was puzzled by the patchiness of forest cover.

“Some of the world’s most productive forests … are growing right next door to huge expanses of exposed bedrock that are so large they can actually be seen from space,” Hahm said. “And the climate in this area is perfect for those forests, which suggests that something else must be driving the presence and absence of vegetation.”

Hahm’s team found that the bedrock in the bare areas had a different chemical makeup than the bedrock in the forested areas. He says that helps explain the patchiness of forests, and could shed light on how forests may change in the future.

“Forests in California, especially the Sierra Nevada, are expected to warm in the coming century,” he said. “And that translates into a northward migration of forests, as well as a migration up in elevation. And as those forests are migrating to new habitable areas, they may also be restricted by the underlying bedrock and the chemical composition of that bedrock.”

The research was conducted in California, but Hahm says Wyoming’s forests have a lot in common with the ones he studied. The study was published in the journal Proceedings of the National Academy of Sciences.